This project will develop powerful new tools to determine when and where proteins are made in complex cellular systems. Reactive amino acid analogs will be incorporated into cellular proteins and selectively conjugated to probes for visualization, isolation and identification of newly synthesized proteins in both prokaryotic and eukaryotic cells. Most importantly, these approaches can provide both spatial and temporal resolution in analysis of cellular protein synthesis. Cell-selectivity is achieved by controlled expression of mutant aminoacyl-tRNA synthetases; in systems containing multiple cell types, amino acid labeling is confined to cells in which the mutant synthetase is active. This project will explore the use of such methods to elucidate the mechanisms by which bacteria evade the defenses of mammalian hosts, to examine the process of quorum sensing (which is essential to the expression of virulence by bacterial pathogens), and to interrogate protein synthesis in a cell-selective manner in the model organism Caenorhabditis elegans. These studies will establish powerful, general platforms for systems-level characterization of biological phenomena ranging from development to the treatment of disease. PUBLIC HEALTH RELEVANCE: This project will provide new methods to elucidate the mechanisms by which bacteria attempt to evade the defenses of their mammalian hosts, to examine how bacteria communicate with one another to express virulence factors and form antibiotic-resistant biofilms, and to identify the different sets of proteins made by individual cells in living animals. These studies will establish new windows on biological phenomena ranging from growth and development to the treatment of infectious disease.